Threats to woodland in an urban landscape: A case study in Greater London

The area of ancient semi-natural woodland in south-east London (Oxleas Wood) threatened by the construction of the East London River Crossing is analysed in terms of its extent, species richness, rarities, age-class structure and tree regeneration. A detailed study of its history produced evidence which concurred with data from coring trees on the date of origin of the stand and it is argued that understanding habitats of this type in terms of the past adds to the value of the site because of the benefits available to site interpretation. The site is an SSSI and the reasons for this designation are briefly presented. The problems of recreating ancient woodland are discussed and the value of the site to schools and other groups is also considered.     

Estimating slope failure potential in an earthquake prone area: a case study at Skolis Mountain, NW Peloponnesus, Greece

One of the most important issues in the evaluation of geological hazards is the delineation of landslide prone areas and the estimation of the slope failure potential. In this study, the GIS-based Newmark’s displacement method was applied for the first time in Greece, in order to compute the permanent displacement values and evaluate the slope failure potential in the area of the Skolis mountain in NW Peloponnesus, Greece. The resulting maps were validated using the distribution of secondary effects triggered by the 8 June 2008 earthquake. The study indicated that as the source areas of the rock falls were delineated by the Newmark displacement method, this may be a useful approach to predict earthquake-induced slope failures when the seismic potential of an area has been previously evaluated.     

Emissions variation in urban areas resulting from the introduction of natural gas vehicles: Application to Barcelona and Madrid Greater Areas (Spain)

On-road traffic is the major contributor to pollutant emissions in urban areas. Nowadays different emission abatement strategies are being tested in order to improve urban air quality (e.g. the European Commission currently promotes the use of natural gas as an alternative fuel). Several feasible scenarios regarding the introduction of natural gas vehicles (NGV) are studied in the two main cities of Spain (Barcelona and Madrid) by using the HERMES emission model. The most suitable emission factors to NGV are selected among those available in the literature. The account of emissions in the base case scenario estimated for a typical summertime polluted day of the year 2004 reflects that in Barcelona 86% of primary pollutants come from on-road traffic compared to 93% in Madrid, because of the heavier industrial activity in the former. The introduction of NGV in urban zones would have a positive effect on emissions, whose extent largely depends on the substituted fleets and the conurbation characteristics. Maximum reductions in NO_x emissions in Madrid are attributed to the substitution of 10% of the oldest diesel and petrol cars, while in Barcelona the change of 50% of the oldest commercial light vehicles becomes more effective. PM_2.5 and SO₂ emissions can be significatively reduced with the introduction of NGV instead of the oldest commercial light vehicles. The substitution of conventional fuels by natural gas must reach around 4% to achieve significative reductions in traffic emissions (larger than 5%). This work focuses on air quality issues, therefore GHG emissions are not included, nevertheless this kind of associated impact has to be considered by the decision makers. Assessing the efficacy of environmental improvement strategies entails a realistic design of emission scenarios and their evaluation. The detailed emission account provides a fundamental basis for the air quality modelling and its comparison among scenarios.